Adducts of delta-aminobenzylpenicillin and n-substituted-4-piperidones

ABSTRACT

6-(Substituted-1,3,8-triazaspiro(4.5)decan-1-yl) penicillanic acids are described which exhibit antibacterial properties and whose solubility characteristics can be readily altered to permit wider versatility in their use as antibacterial agents.

United States Patent [191 McCaully et al.

3,725,389 Apr. 3, 1973 ADDUCTS OF DELTA- AMINOBENZYLPENICILLIN AND N- SUBSTITUTED-,4-PIPERIDONES Inventors: Ronald J. McCaully, Malvern; Stanley C. Bell, Penn Valley; George L. Conklin, Havertown, all of Pa.

American Home Products Corporation, New York, NY.

Filed: July 2, 1971 Appl. No.: 159,573

Assignee:

U.S. Cl ..260/239.1, 424/271 Int. Cl. ..C07d 99/16 Field of Search ..260/239.1, 240 C [56] References Cited UNITED STATES PATENTS 3,351,587 11/1967 Album et a1. ..260/239.l

Primary ExaminerNicholas S. Rizzo Attorney-Vito Victor Bellino et al.

[57] ABSTRACT 7 Claims, No Drawings ADDUCTS F DELTA- AMINOBENZYLPENICILLIN AND N- SUBSTITUTED-4-PIPERIDONES This invention relates to novel 6-(substituted-1,3,8 triazaspiro [4.5 ]decan-1-yl penicillanic acids.

One aspect of the present invention is to provide novel penicillanic acid derivatives exhibiting antibacterial activity and possessing chemical and physical properties that permit versatility in mode of administration.

Another aspect of the present invention is to provide N-substituted 6-( l ,3 ,S-triazaspiro [4.5 ]decanl-yl penicillanic acids in which the nitrogen substituent may be adjusted so as to impart to the product solubility characteristics which will affect absorptionof the compound and break down rate to ampicillin.

A further aspect of the present invention relates to the preparation of the novelty products of the present 20 isolated by aqueous extraction of the penicillin adductinvention.

The novel 6-(substitutedl ,3,8-triazaspiro[ 4.5]decan-l-yl) penicillanicacids are represented by the structural formula wherein R is a member selected from the class consisting of aroyl, ara(lower)alkyloxy carbonyl and C -C hydrocarbon acyl. The term lower alkyl means a hydrocarbon radical having C to C carbon atoms (e.g. methyl, ethyl, propyl, butyl). The term aroyl means monoand bicyclic hydrocarbons examplified by benzoyl and naphthoyl. The term ara means phenyl, naphthyl and substituted phenyl wherein the substituent is selected from the class consisting of (lower)alkyl having C C carbons, halogen (Cl, Br, F,

etc.) and (lower)alkoxy having C -C carbons. The

term hydrocarbon acyl means both straight chain and branch chain radicals, either saturated or unsaturated as exemplified by acetyl, propionoyl, hexanoyl, octanoyl, decanoyl, t-butyroyl, dodecanoyl, tetradecanoyl, etc.

The compounds of formula I also include the corresponding non-toxic pharmaceutically acceptable salts such as (1) salts of the acidic carboxylic acid group, such as the sodium, potassium, calcium, aluminum and ammonium salts; amine salts; acid addition salts (i.e., salts of the basic nitrogen) exemplified by mineral acid addition, such as hydrochloride, sulfate,

phosphate, sulfamate; organic acid addition, such as N-substituted-4-piperidone according to the equation:

The method of preparation of the compounds of formula I is carried out by stirring a solution of aaminobenzylpenicillin and the appropriately N-substituted-4-piperidone in an inert solvent (e.g., chloroform, benzene, 1,2-dichloroethane, methylene chloride, etc.) in the presence of a tertiary lower alkyl amine (e.g. triethylamine) at a temperature between 20-40 C. for 10-36 hours. This reaction may be run exposed to the atmosphere but is preferably carried out in an inert atmosphere. The reaction product is then tertiary alkyl ammonium salt from the organic solvent followed by adjustment of the pH of the aqueous extract to pH 2-3 with dilute mineral acid (e.g. l to 5N) whereby the solid adduct separates from solution as white crystals.

In carrying out the foregoing process it is preferred to remove the excess tertiary (lower) alkyl amine prior to aqueous extraction by evaporation in vacuo of the inert organic solvent and excess solvent. The residue isv then redissolved in the organic solvent and extracted with water as previously described. Final isolation of the product may also be facilitated if the aqueous solution is, chilled and the acid neutralization is carried out step-wise. The solution is adjusted to pH 7, seeded and filtered from unaltered a-aminobenzyl-penicillin. The process may be repeated at pH 5 to remove additional unaltered a-aminobenzylpenicillin.

Depending on the nature of the R substituent in formula I the solubility properties of some of the products embraced by such formula is such that they will not separate from aqueous solution in the pH range of 2-3 and they must therefore be isolated by lyophilization of the aqueous solution. Therefore, it is necessary that the tertiary (lower)alkylamine hydrochloride and unaltered a-aminobenzyl-penicillin be removed when the product of formula I is isolated by lyophilization.

The N-substituted-4-piperidones used to prepare the products of the present invention may be prepared in accordance with the procedures described by Mo Elvain et al. in J. Am. Chem. Society, 71, 901 (1949) and H. H. Kuehnis, is, H. Rfy and R. Denss, Swiss Pat. No. 447,163, Mar. 1968 the disclosure of which is incorporated herein by reference.

The following examples are illustrative of the products and processes of the present invention.

EXAMPLE 1 6( 8-Ben2oyl-2-Oxo-3-Phenyll ,3 ,8Triazaspiro [4.5 ]Decan-1-yl)Penicillanic Acid A solution of 5.0 g. of a-aminobenzylpenicillin and 2.9 g. of N-benzoyl-4-piperidone in ml. of methylene chloride and 3.0 g. of triethylamine are stirred at 26 for 24 hours in a nitrogen atmosphere. The cloudy solution is filtered through filter-cell and poured into icewater. The two phase mixture is thoroughly agitated and the aqueous phase separated. Gradual acidification of the aqueous phase with 3N hydrochloric acid to pH 2.5 afforded 1.1 g. of above-titled product. Analysis: Calculated for C H N O S'1%H O: C,59.87; I-I,5.92; N, 9.98 V

Found C,59.87; H,5.54; N,10.05 IR spectrum (KBr) exhibited bands at 5.64 (,B-lactam), 5.90 (broad) and 6.21 (broad).

EXAMPLE 2 6-( 8-Acetyl-2-Oxo-3-Phenyll ,3 ,8-Triazaspiro [4.5 ]Decan-1-yl)Penicillanic Acid A solution of 5.0 g. of a-aminobenzylpenicillin and 2.0 g. of N-acetyl-4piperidone in 100 ml. of methylene chloride and 3.0 g. of triethylamine are stirred at 26 for 24 hours in a nitrogen atmosphere. The solution is extracted with two portions of water. The combined aqueous extracts are acidified to pH 2.0 and the sticky, amorphous solid that separated is filtered. The filtrate is freeze dried to a white powder and the powder is slurried two times in 12 ml.-portions of water. The small quantity of undissolved solid is dissolved in 180 ml. of water and freeze driedv to 400 mg. of the above-titled product. Analysis: Calculated for C,53.37; H,6.42; N,10.82

Found C,52.84; H,5.97; N,l0.92 The IR spectrum exhibited bands at 5.63 (B-lactam), 5.88(broad) and 6.21 (broad).

EXAMPLE 3 6-( 8-Carboxy-2-Oxo-3-Phenyl-1 ,3 ,8-Triazaspiro- [4.5 ]Decanl -yl)Penicillanic Acid, 6-Benzyl Ester A solution of 5.0 g. of a-aminobenzylpenicillin and 3.3 g. of N-carbobenzyloxy-4 piperidone in 100 ml. of methylene chloride and 3.0 g. of triethylamine are stirred at 26 for 24 hours in a nitrogen atmosphere. The solvent and excess triethylamine are evaporated in vacuo at room temperature and the oily residue is dissolved in 100 ml. of cold water. The water is extracted with ether and then acidified to pH 6.8-7.0 with 3 N hydrochloric acid. The unaltered a-aminobenzylpenicillin separated out and is filtered off. The filtrate is acidified with 3 N hydrochloric acid to pH 2.5 whereupon 1.1 g. of the above-titled product is obtained. Analysis: Calculated for C H N O S-H O: C, 59.78; H, 5.88; S, 5.50

Found C, 59.76; H, 5.71; S, 5.39 The IR spectrum of the product exhibited bands at 5.64 (B-lactam) and 5.96 (broad).

EXAMPLE 4 The condensation of a-aminobenzylpenicillin and N- carbo-benzyloxy-4-piperidone (in 50 percent molar excess) is carried out as described in Example 3. The yield of 6-(8-carboxy-2-oxo-3-phenyl-1,3 ,8-triazaspiro- [4.5]decan-l-yl) penicillanic acid, 6-benzyl ester was unaffected by the excess Ncarbobenzyloxy-4- piperidone.

EXAMPLE 5 6-( 8-Octanoyl-2-Oxo-3-Phenyll ,3 ,S-Triazaspiro [4.5 ]Decanl -yl)-Penicillanic Acid A solution of 5.0 g. of a-aminobenzylpenicillin and 3.2 g. of N-octanoyl-4-piperidone in 100 ml. of

methylene chloride and 3.0 g. of uiethylamine are stirred at 26 for 24 hours under nitrogen atmosphere. The solvent and excess triethylamine are evaporated in vacuo. The residue is dissolved in ml. of cold water and the solution is extracted with ether containing a small quantity of heptane. The aqueous phase is adjusted to pH 6.8 and seeded with a-aminobenzylpenicillin. After filtration of the unaltered aaminobenzylpenicillin (2.8 g.), the filtrate is acidified to pH 4.7 and refiltered from a small quantity of sticky gum by passage through a filter-cell cake. Upon acidification of the filtrate to pH 2.7, 0.7 g. of the above-titled product separated. Analysis: Calculated for C H N O S'H O: C, 60.60; H, 7.36; N, 9.75; S,5.58

Found C, 60.78; H, 7.25; N, 9.79; S,5.72 The IR spectrum of the product had bands at 5.62 (B- lactam), 5.86 (CO) and 6.15-6.30 (broad).

EXAMPLE 6 When in the procedure of Example 1, the N-benzoyl- 4-piperi-done is replaced by 1. N-hexanoyl 4-piperidone 2. N-tetradecanoyl 4-piperidone respectively, the following corresponding penicillin adducts are produced:

1 6-( 8-hexanoyl-2-oxo-3-phenyl- 1 ,3 ,8-triazaspiro[ 4.5 ]decan-1-yl) penicillanic acid 6-( 8-tetradecanoyl 2-oxo-3-phenyl- 1 ,3 ,8- triazaspiro[4.5 ]deca.n- 1-yl)penicillanic acid.

The compounds of formula I of this invention have been found to possess antibacterial activity. Antibacterial screening is carried out by an agar serial dilution technique. Distilled water is used as a vehicle. The stock solution is prepared at 10,000 ug/ml. of substance in the vehicle. Two-fold dilutions are made with sterile water. One ml. quantities of each dilution are incorporated into 9 ml. seed agar in sterile petrie dishes. The hardened surface is inoculated with test organisms and incubated 18 hours at 35 C. The end point is reported as a minimal inhibitory concentration (MIC) expressed in ug./ml.; the least amount of test substance that will completely inhibit the test organism.

The following table is illustrative of the antibacterial properties of the compounds of the present invention:

Compound of MIC Example Test Organ'mm g./ml. 1 Bacillus subtilis 6633 0.244 2 Bacillus subtilix 6633 0.244 3 Bacillus subtilis 6633 0.122 1 Escherichia coli 6880 3.90 2 Escherichuz coli 6880 7.81 3 Ercherichia coli 6880 1.95 1 Suzphybcoccus aureus 6538 P 0.244 2 Staphylococcus aureus 6538 P 0.488 3 v Staphylococczc aureus 6538 P 0.244 1 Staphylococcus aureus CHF 62.5 2 Staphylococcus aureus CHP 62.5 3 Staphykxoccus aureus CHP 3 1.3

The foregoing examples of antibacterial activity are merely given to illustrate the utility of the compounds of the present invention and such compounds have demonstrated antibacterial activity against other test organisms.

The in vivo antibacterial activity of the compounds of the present invention has been substantiated in mice. The compound of Example 1 exhibits upon subcutaneous administration in mice an ED against streptococcus pyogenes C203 of 0.42 mg. per kg. The compound of Examples 2 and 3 gave a ED against the same organism of 0.425 and 0.393 mg./kg. respectively, as determined by the method of Reed and Muench, American Journal of Hygiene, 27, 493 (1938).

The compounds of this invention have been designed to breakdown gradually to ampicillin so that the ampicillin activity would be of a longer duration. The rate of breakdown would be affected by the size of the R- group. Alterations in the R-group also cause changes in the hydrophilic and lipophilic properties of the compounds. Changes in these properties could be expected to alter the selective absorption of the compounds at various sites in the body.

The above alterations in the properties of the compound would be especially important when the compounds are administered intramuscularly as a depot injection. For a depot injection the medium could be variedso that the compounds are dissolved or in suspension.

Unlike the previous derivatives of ampicillin (namely the hetacillin family) the compounds of this invention permit more facile and greater variations in the physi cal properties of the penicillins without introducing the complications that accompany the addition of new chiral centers.

What is claimed is:

l. A compound selected from the class consisting of those having the formula wherein R is a member selected from the class consisting of benzoyl, naphthoyl, C -C hydrocarbon acyl, phenyl(lower)alkyloxycarbonyl, naphthyl(lower)alkyloxycarbonyl and substituted phenyl(lower)a.lkyloxycarbonyl, said substituent being selected from the class consisting of C -C alkyl, halo and C C alkoxy;

wherein R is a member selected from the class consisting of benzoyl, naphthoyl, C -C hydrocarbon acyl, phenyl(lower)a1kyloxycarbonyl, naphthyl(lower)alkoxy carbonyl, and substituted phenyl(lower)alkyloxycarbonyl, Said slr i t asi iet ifrqmt e class consisting of C1-C (alkyl, halo and C1-C alkoxy; which comprises reacting a-aminobenzyl penicillin with a compound of the formula in the presence of an inert organic solvent and a trialkylamine, said reaction being carried outat a temperature between about 20 and about 40 C.

7. A process according to claim 6 wherein said reaction is carried out in an inert atmosphere. 

2. The compound of claim 1 which is 6-(8-benzoyl-2-oxo-3-phenyl-1,3,8-triazaspiro(4.5)decan-1-yl)penicillanic acid.
 3. The compound of claim 1 which is 6-(8-acetyl-2-oxo-3-phenyl-1,3,8-triazaspiro(4.5)decan-1-yl)penicillanic acid.
 4. The compound of claiM 1 which is 6-(8-carboxy-2-oxo-3-phenyl-1,3,8-triazaspiro(4.5)decan-1-yl)penicillanic acid, 6-benzyl ester.
 5. The compound of claim 1 which is 6-(8-octanoyl-2-oxo-3-phenyl-1,3,8-triazaspiro(4.5)decan-1-yl)penicillanic acid.
 6. The process for preparing a compound selected from the group consisting of those having the formula:
 7. A process according to claim 6 wherein said reaction is carried out in an inert atmosphere. 